The present disclosure relates generally to peritoneal dialysis, and in particular to peritoneal dialysis systems useful in manipulating the number of cycles, drain volumes and fill volumes in a multi-cycle dialysis therapy. The calculations and manipulations are useful in assuring use of all or nearly all a prescribed dialysis solution volume in treating a particular patient during a particular therapy.
Automated Peritoneal Dialysis (“APD”) is a natural evolution of Continuous Ambulatory Peritoneal Dialysis (“CAPD”), in which the patient introduces the entire contents of a dialysate solution bag into his/her peritoneum and allows the volume to dwell for three to six hours. After the dwell period, the fluid is drained using gravity. The above process is typically repeated three or four times each day as necessary. Working adults may perform an exchange at home before leaving for work, one at work during their lunch hour, one when the patient arrives home from work and one just before the patient goes to bed. Some school-aged patients follow a similar routine except that they perform their mid-day exchange at school.
APD machines (sometimes called “cyclers”) perform sequential exchanges during the night when the patient is sleeping, making APD a more convenient therapy. Also, the treatment is carried out in the privacy of the patient's home, so that others do not have to know that the patient is on dialysis. It is no surprise that most patients would prefer APD over CAPD.
However, there are some important differences between CAPD and APD. CAPD is typically performed with the patient sitting upright in a chair, whereas APD is performed with the patient lying down. The patient's internal catheter may work its way down into the bottom of the patient's peritoneal cavity (pelvic area) during the day when the patient is ambulatory so that it is not in an optimum position for draining when the patient is in a prone or sleeping position. Even with the catheter in the correct position, a supine or sitting position is generally better for draining than is the prone or sleeping position. Thus APD treatments can experience incomplete drains.
Continuous Cycling Peritoneal Dialysis (“CCPD”) is one popular APD therapy because it performs a full drain after every dwell, minimizing the potential for overfill due to the fluid that is ultrafiltered from the patient's body. CCPD can however present a challenge when a patient does not drain well. In a night therapy, the patient cannot be awakened every 1.5 hours, so that the patient can sit up and ensure a complete drain.
Accordingly, APD cyclers in some instances advance from drain to fill after a minimum percentage of the patient's previous fill volume has been drained, for example, when the drain flow rate has slowed down to a point that time is being wasted that could be used for therapeutic benefit. Alarms will typically be posted if the drain flow rate slows to a certain rate before the minimum drain percentage has been exceeded. The HomeChoice/Pro® APD cycler, provided by the assignee of the present disclosure, is considered one of the best draining cyclers on the market, producing fewer alarms when compared to its competitors. Even still, low drain volume alarms occur relatively frequently.
An APD cycler with improved drain control is needed accordingly.